Apple's 2012 iMac models began shipping on Friday, and some have landed in the hands of experts who have put the all-in-one desktop computer to the test. Here's a round-up of what the critics had to say about the brand new iMac. 

"It is incredibly slim… a few years ago, this could have been mistaken for a standalone flat-panel display. But the new iMac is a powerful all-in-one that should meet the needs of all but the most demanding of users," writes Fortune's JP Mangalindan.

Fortune's review notes that the lack of an optical drive may mean that the new iMac isn't an ideal solution for some, but for those who download or stream music and video, it's a "non-issue".

Mangalindan claims to have put the new iMac through its paces, running multiple applications at ones and spending hours playing Call of Duty 4: Modern Warfare on it, with not an issue to speak of. He notes that the fan did fire up, but stayed quiet.

Fortune's review explains that the non-Retina display on the new iMac won't bother those who aren't used to a Retina MacBook Pro, and that the new screen with up to 75 per cent less glare seems to have made a big improvement.

Mangalindan's only gripe was the iMac's speakers, which are "nowhere near horrible," but lacking in bass. A separate pair of speakers is mandatory for audiophiles, he says.

"It is the biggest iMac product redesign in years and a largely successful one, provided some users don't mind shelling out a little extra for the optical drive or overlooking this generation's omission of Retina Display," Mangalindan concludes.

David Pierce at The Verge wrote: "This year's iMac appears to have undergone the computer version of elective cosmetic surgery – it doesn't look different, just better."

While he notes that "Apple's claim of it being 5mm thin is a bit misleading," due to the iMac's bulging back, Pierce said that it is "incredibly sleek" and "good looking".

Pierce says that he misses the optical drive in the iMac, and doesn't think it makes as much sense to remove it as it did on laptops. He also dislikes the repositioning of the SD card slot, which is now on the back of the iMac, alongside the headphone jack, four USB 3.0 ports, Thunderbolt port, and a Gigabit Ethernet port.

Pierce agrees with Mangalindan in that the iMac's speakers are poor. "I always loved the iMac's speakers… but in the newer, slimmer model, they're actually a step backward….Mid and highs sound great, and the down-firing speakers are loud enough to fill a room, but there is absolutely zero bass response," he explains.

As for the display, Pierce writes that "if you get close to the screen, you can definitely see individual pixels, but at normal using-a-computer distances, they look crisp and sharp."

"Indeed the glare problems that beset so many displays are much less present here, though there's still some reflection and glare," he says. "The improved manufacturing also makes whatever's on the screen feel closer to you, almost like things are jumping out of the panel."

Pierce also notes that the iMac didn't show any sign of struggling when running multiple apps and games, and that the optional Fusion Drive, which will set you back an additional £200, "works just as it should, especially if you're coming from a hard drive-based machine," and feels "blisteringly fast."

Overall, Pierce's 2012 iMac review concludes: "The display is really the only unequivocated improvement in the new model, and it’s a big one. The sleeker, slimmer design is great, but it causes a couple of problems and forces a few unfortunate compromises. Yes, it’s faster, but only enough to keep up with the Joneses - equal performance can definitely be had elsewhere."

"There’s no question this is the best iMac yet, but of course it is; Apple doesn’t have a habit of making its good products worse. If you weren’t in the market for a new all-in-one desktop, the iMac’s not suddenly so much more appealing that you absolutely have to have one now, but if you’re looking for a desktop PC there’s still no better option."

TechCrunch's Darrell Etherington says that the new iMac's thinner design is impressive, but that all of that trimming has led to some omissions such as the built-in optical drive and, in the 21.5in model, user-accessible RAM. Despite this, Etherington says "this revamped iMac hardware is a huge improvement over previous generations in just about every way that matters."

Ethertington noted a "considerable" difference in the display's reflectiveness, and says that the screen feels "much improved in all tasks," especially photo editing.

Etherington's benchmark scores showed that the 2012 iMac has solid improvements over its predecessors, and his non-Fusion review unit "truly impressed in terms of executing every day tasks."

Interestingly, when it came to the speakers, Etherington disagreed with the previous two reviewers on the sound quality, describing the new iMac's built-in speakers as "better" than predecessors.

Engadget reviewer Dana Wollman found the new iMac's skinnier design 'eye-catching' but sees it as just a bonus, noting that the only time you'll ever notice it is when you're looking at your computer edge-on, which is something we don't do particularly often.

Wollman says that the iMac's wow factors are the display, sound and an impressive performance that means little waiting. She describes Apple's attempt to reduce glare on the display as a "success" and highlights the improvement in colour.

She agrees with Etherington in that the iMac's speakers are improved, and goes as far as saying "you probably don't need an external pair of speakers; as is, we felt we were rediscovering favourite songs, in that we were able to make out details that would have gotten drowned out on a lesser system."

"The newest iMac is a great product, and despite Apple's reputation for making pricey things, it's actually a great value, too…As for FusionDrive, it's exceedingly rare to find a consumer system that uses an HDD for storage and an SSD for system stuff. That's a clear step up from typical hybrid drives, which use a much smaller amount of flash memory, mainly for caching and improving start-up times. And while Apple doesn't always win on specs, it makes a tempting offer here: you get beefier graphics than on competing systems, which should help creative professionals, amateur photographers and casual gamers alike," Wollman concludes, highlighting the lack of an optical drive as the only real drawback for some consumers.

CNET's Rich Brown gives the new iMac an 'excellent' rating, writing "Apple sticks to the fundamentals with the new iMac, relying on design, strong features, and overall polish to maintain its leadership among high-end all-in-ones."

Brown says that the 27in iMac is an easy recommendation for those who need or want a fast computer with a large, "gloriously crisp" display. "The new design simply looks fantastic," he says.

When it comes to Apple's new antireflective display, Brown writes that the benefits are "immediately apparent if you set the iMac up next to other large-screen monitors."

"On the whole, the 27in iMac seems fairly priced," Brown said. "The lack of an optical drive is inconsequential given how easy it is to add an external DVD burner. I also don't miss FireWire 800 on the iMac. Both USB 3.0 and Thunderbolt are faster. I only wish Apple provided a dedicated HDMI input."

 As for performance, Brown said: "This is the fastest iMac yet, and one of, if not the, fastest all-in-ones available."

Brown gave credit to the iMac's new, second microphone for its ability to improve sound quality of a FaceTime call.

In conclusion, Brown wrote: "You might be alarmed by the fact that the design is the most interesting thing about the new iMac. A thin bezel is nice to look at, but it doesn't improve processing speed, workflow, or overall utility. Fortunately for Apple, it evolved that design from a computer with a strong technical foundation. It is the updates to that foundation, and a few points of polish along the way, that keep this iMac on elite footing. I'll suggest you line up behind the Blu-ray fans to those of you hoping Apple will someday add touch-screen input to the iMac. Instead, this is a computer for serious, performance-driven users, particularly those who need a high-resolution display, and fast graphics and disk performance."

Overall, the majority of reviewers seem to agree that the lack of an optical drive in the new iMac models isn't a major issue. In a recent Macworld poll, 55 per cent of our readers said that they could live with out the CD/DVD drive on their Mac.

The reviewers also agreed that the display and performance of the iMac is much improved, and that the thinner design is one of the most impressive new features of the computer.

What they don't seem to agree on, however, is the quality of the speakers, with the reviewers completely torn over whether they are amazing or appalling.

We'll soon be bringing you our very own review of Apple's new iMac models, with our expert opinion on its pros and cons and our advice about whether or not you should buy one.

In the meantime, you can find out more about the new iMacs by following the links below:

It's easy to upgrade RAM on new 27in iMac 2012

Upgrading RAM on new 21.5in iMac 2012 practically impossible

Mysterious 'Assembled in USA' label spotted on new iMac 2012 models

Apple selling 21in skinny iMac, taking 27in pre-orders for delivery this month

It will give your Mac a boost, but is Apple's Fusion Drive a rip off?